Imagine you're blindfolded and you're getting the best raw pornstar-grade blowjob in the entire universe. The catch is, however, that you'll never figure out who's giving you that god-tier awesome schmosome sloppy toppy unless you take the blindfold off. It could be anybody, Ariana Grande, Ben Shapiro, Harold from the 7-11 near my house, or even your uncle's neighbour's fireman's cat. Now the question is: would you take off the blindfold and find out who the person/thing behind the stupendous jimmy-nibbler is and risk permanently scarring yourself, or would you keep the blindfold on and continue having your knob slobbed till your spirit hits the sky?
When a girl has given enough blowjobs, and her knees are red and bruised from being on them so often. Can also happen after a single very long blowjob.
Can also occur after bumping into things, falling over etc.
1) "That girl has a s serious case of blowjob knees"